The major goal of this project is to develop improved therapies for hypercholesterolemia and intravascular thrombosis, two clinical problems which underlie a significant percentage of the cardiovascular morbidity and mortality in the Western world. Much recent work has focused on the genetic basis of these clinical problems, due either to inborn mutations or to inappropriate gene expression. Accordingly, we are attempting to design and implement genetic therapies for these two disease processes. The clearest example of the genetic contribution to hypercholesterolemia is the disease Familial Hypercholesterolemia, in which mutations in the low density lipoprotein receptor gene result in severe hypercholesterolemia. An animal model exists of this disease, the Watanabe rabbit. This rabbit strain also lacks normal LDL receptors and has hypercholesterolemia. We have succeeded in introducing a normal LDL receptor gene into cultured Watanabe rabbit cells, and have reintroduced the cells into the donor rabbits. The receptor bearing cells have been found in tissue sections up to 4 weeks after implantation, demonstrating that in vivo expression of a normal LDL receptor is feasible in this important animal model. A second project involves the overexpression of the tissue plasminogen activator (t-PA) gene in endothelial cells, a potential therapy for intravascular thrombosis. We have determined that overexpression of t-PA results in a net increase in fibrinolytic activity of the cells, and are currently designing means to achieve t-PA overexpression in endothelial cells in vivo.